EP0095267B1 - Hydraulic motor comprising a position transducer - Google Patents
Hydraulic motor comprising a position transducer Download PDFInfo
- Publication number
- EP0095267B1 EP0095267B1 EP83302555A EP83302555A EP0095267B1 EP 0095267 B1 EP0095267 B1 EP 0095267B1 EP 83302555 A EP83302555 A EP 83302555A EP 83302555 A EP83302555 A EP 83302555A EP 0095267 B1 EP0095267 B1 EP 0095267B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- winding
- windings
- hydraulic motor
- signals
- core member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/204—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
- G01D5/2046—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by a movable ferromagnetic element, e.g. a core
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/20—Other details, e.g. assembly with regulating devices
- F15B15/28—Means for indicating the position, e.g. end of stroke
- F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
- F15B15/2861—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using magnetic means
Definitions
- This invention relates to a hydraulic motor of the kind defined in the introductory part of claim 1.
- variable transformers As the sensing devices.
- typical variable transformers such as linear variable displacement transformers with different windings (e.g. US-A-3 289 479 and US-A-3 438 306) which can measure displacements in the range of the stroke of an ordinary hydraulic cylinder which has a stroke length of between 25 and 250 mm, are very expensive.
- a motor in accordance with the introductory part of claim 1 is known from GB-A-883 781.
- the length of the solenoid is equal to the total travel of the control element which means that the ratio of the secondary signals becomes highly indeterminate at one end of the stroke.
- both the core member and the primary winding exhibit significant axial discontinuities so that the ratio will not be a smoothly varying signal. Accordingly it is necessary to provide a separate fine measurement system.
- the object of the present invention is to provide an improved and simpler motor which has a linear response.
- the invention is characterised in the manner set out in claim 1.
- a fluid motor 10 includes a cylinder 12 within which reciprocates a piston 14 and rod 16.
- a blind stepped bore 17 extends axially into the piston 14 and rod 16.
- a housing 18 at the head end of the cylinder 12 receives a screwed-in fitting 20 which rigidly supports one end of a hollow cylindrical coil support tube 22 which is constructed of an electrical insulating material, such as glass- reinforced epoxy resin.
- the tube 22 includes a longitudinally extending groove 24 in its outer surface, as best seen in Fig. 2. The tube 22 almost completely fills the large portion of the bore 17 when the motor 10 is fully retracted.
- the tube 22 and bore 17 are long enough so that part of the tube 22 remains within the piston 14 when the motor 10 is fully extended.
- a magnetic steel core rod 26 is press-fitted into the small portion of the blind bore 17 and extends to an end 28 which is contiguous with the plane of the end face 30 of piston 14.
- a single layer coil of wire is wrapped in a spiral bifilar manner around the outer surface of tube 22 from a position indicated by reference numeral 32 to the end 34 of tube 22.
- One of the filaments of the bifilar wound coil is continuous, extends the entire length of the coil and forms the primary coil 52 or winding of a 3-coil or winding transformer.
- the other filament is broken into two coil or winding portions, one of which extends from 32 to a position indicated by reference numeral 36 and is hereinafter referred to as the displacement coil 54.
- the remaining portion of the other filament extends from 36 to 34 and forms what will be hereinafter referred to as the reference coil 56.
- the leads to the various coils are routed through and along the groove 24, but are shown removed from Fig. 2 for clarity.
- the displacement coil 54 extends from 32 to 36 and is longer than the stroke of the piston 14.
- the reference coil 56 extends from 36 to 34 and is totally penetrated by at least a portion of the core 26, regardless of the position of the piston 14 and rod 16 with respect to the cylinder 12.
- the break between the secondary coils 54 and 56 may be positioned at various places so as to vary the relative lengths of the displacement and reference coils while their overall or combined lengths remain substantially equal to the length of the primary coil (which extends from 32 to 34). Satisfactory operation may be obtained for ratios of displacement to reference coil lengths varying from a ratio of 6 to 1 to a ratio of approximately 7 to 1. It should further be noted that the end 32 of the coils is placed a finite distance beyond the end 28 of the core 26.
- the following dimensions are given by way of example only to illustrate dimensions which have been found to be suitable for a fluid motor as shown in Fig. 1 with a 200 mm stroke.
- the distance between 32 and 28 is 12.5 mm; the distance between 32 and 36 is 250 mm; and the distance between 36 and 34 is 40 mm.
- Fig. 3 schematically shows a circuit 50 for exciting the primary coil 52 and for deriving a position representative signal from the voltages across the displacement coil 54 and the reference coil 56.
- Circuit 50 includes a sinusoidal signal generator 58 which applies to the primary coil 52, an AC sinusoidal signal with a peak-to-peak voltage of approximately 10 volts and a current which varies from 75 to 150 milliamperes, approximately, depending upon the position of the core 26 relative to the coils.
- a conventional AC-to-DC converter 60 converts the induced sinusoidal voltages across the displacement coil 54 and the reference coil 56 to DC voltages Vdsp and Vref, respectively.
- the voltage Vref is applied to the Vr input of an analog-to-digital converter 62, such as National Semiconductors ADC 0831, which is an A/D converter with serial input/output, compatible with 8-bit microprocessors.
- the voltage Vdsp is applied to the Vin input of the converter 62.
- a 5 to 10 kilohertz squarewave clock signal is applied to the clock input C of the converter 62.
- the converter 62 generates at its 1/0 output terminal a serial digital output signal, Vo, which is proportional to the ratio of the voltage Vdsp to the voltage Vref.
- This ratiometric digital output signal Vo has a desirable linear dependence upon the position of the piston 14 within the cylinder 12 and thus provides an accurate indication of the positional status of the fluid motor 10. Any temperature or impurity-induced variations in the voltages across the displacement and reference coils, 54 and 56, are cancelled out by the division which creates the ratio voltage Vo. Thus, the output Vo is substantially independent of temperature or impurity effects.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Actuator (AREA)
- Fluid-Pressure Circuits (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT83302555T ATE19134T1 (de) | 1982-05-10 | 1983-05-06 | Hydraulikmotor mit stellungsgeber. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US37647682A | 1982-05-10 | 1982-05-10 | |
US376476 | 1982-05-10 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0095267A1 EP0095267A1 (en) | 1983-11-30 |
EP0095267B1 true EP0095267B1 (en) | 1986-04-09 |
Family
ID=23485174
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83302555A Expired EP0095267B1 (en) | 1982-05-10 | 1983-05-06 | Hydraulic motor comprising a position transducer |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP0095267B1 (ja) |
JP (1) | JPS58208601A (ja) |
AR (1) | AR242448A1 (ja) |
AT (1) | ATE19134T1 (ja) |
AU (1) | AU1429683A (ja) |
BR (1) | BR8302420A (ja) |
CA (1) | CA1196708A (ja) |
DE (2) | DE95267T1 (ja) |
DK (1) | DK207883A (ja) |
ES (1) | ES522204A0 (ja) |
ZA (1) | ZA833291B (ja) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4855675A (en) * | 1984-05-21 | 1989-08-08 | Sacol Powerline Limited | Inductive transducers for indicating establishment of a preselected spatial relationship between two parts |
FR2601664B1 (fr) * | 1986-07-18 | 1988-11-18 | Peugeot | Verin electrique a vis creuses a billes |
DK165562C (da) * | 1987-02-20 | 1993-04-26 | Niels Hvilsted | Hydraulisk cylinder med indbygget induktiv stempelpositionsgiver. |
AU6827090A (en) * | 1990-12-20 | 1992-07-09 | John Edward Hayter | Electromagnetic position transducer |
DE4203192A1 (de) * | 1992-02-05 | 1993-08-12 | Bosch Gmbh Robert | Arbeitszylinder mit einem kolbenweg-messwertgeber |
DE20106298U1 (de) | 2001-04-10 | 2001-06-21 | Festo Ag & Co | Linearantrieb |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3289479A (en) * | 1964-10-05 | 1966-12-06 | Camco Inc | Differential pressure sensing transducer |
US3438306A (en) * | 1967-02-07 | 1969-04-15 | Lear Siegler Inc | Preloaded servo actuator controls for redundant systems |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB883781A (en) * | 1957-01-16 | 1961-12-06 | Atomic Energy Authority Uk | Improvements in or relating to apparatus for the measurement, indication or detection of position of an object |
EP0074301A3 (en) * | 1981-08-28 | 1985-05-22 | The Bendix Corporation | Linear position sensor |
-
1983
- 1983-03-24 CA CA000424391A patent/CA1196708A/en not_active Expired
- 1983-05-05 AR AR83292948A patent/AR242448A1/es active
- 1983-05-06 DE DE198383302555T patent/DE95267T1/de active Pending
- 1983-05-06 AU AU14296/83A patent/AU1429683A/en not_active Abandoned
- 1983-05-06 EP EP83302555A patent/EP0095267B1/en not_active Expired
- 1983-05-06 AT AT83302555T patent/ATE19134T1/de not_active IP Right Cessation
- 1983-05-06 DE DE8383302555T patent/DE3362882D1/de not_active Expired
- 1983-05-09 ES ES522204A patent/ES522204A0/es active Granted
- 1983-05-09 ZA ZA833291A patent/ZA833291B/xx unknown
- 1983-05-09 BR BR8302420A patent/BR8302420A/pt unknown
- 1983-05-10 DK DK207883A patent/DK207883A/da not_active Application Discontinuation
- 1983-05-10 JP JP58081603A patent/JPS58208601A/ja active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3289479A (en) * | 1964-10-05 | 1966-12-06 | Camco Inc | Differential pressure sensing transducer |
US3438306A (en) * | 1967-02-07 | 1969-04-15 | Lear Siegler Inc | Preloaded servo actuator controls for redundant systems |
Also Published As
Publication number | Publication date |
---|---|
AU1429683A (en) | 1983-12-15 |
ES8500396A1 (es) | 1984-10-01 |
DE95267T1 (de) | 1984-05-10 |
ZA833291B (en) | 1984-12-24 |
ES522204A0 (es) | 1984-10-01 |
BR8302420A (pt) | 1984-01-10 |
DE3362882D1 (en) | 1986-05-15 |
JPS58208601A (ja) | 1983-12-05 |
CA1196708A (en) | 1985-11-12 |
DK207883D0 (da) | 1983-05-10 |
ATE19134T1 (de) | 1986-04-15 |
EP0095267A1 (en) | 1983-11-30 |
DK207883A (da) | 1983-11-11 |
AR242448A1 (es) | 1993-03-31 |
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